“The wonderful thing about these HPV vaccines is that when people are vaccinated before [they are] exposed [to the virus], they get a very robust immune response to the vaccine, and it is very protective against cervical and anal cancers,” said Gypsyamber D’Souza, PhD, associate professor at Johns Hopkins Bloomberg School of Public Health in Baltimore, who added, “We are hopeful that the vaccine is also protective against oropharyngeal cancers, since these cancers are caused by the same HPV types.”
Explore This IssueAugust 2013
HPV Vaccine and Oropharyngeal Cancers
The prevention of oropharyngeal cancers is a growing need given a dramatic increase in the incidence of these cancers over the past 20 years. A study published in 2011 showed a 225 percent increase in the incidence of oropharyngeal cancers from 1988 to 2004, and 90 to 95 percent of these cancers are due to HPV infection with the serotype strain 16 (J Clin Oncol. 2011;29:4294-4301).
Although current FDA recommendations do not include the use of the HPV vaccine to prevent oropharyngeal cancers, it is widely believed that the vaccine would be effective in preventing HPV-related oropharyngeal cancers. The lack of FDA recommendation for this indication is due to the difficulty involved in proving the efficacy of the vaccine for these cancers.
According to Erich Sturgis, MD, MPH, professor in the departments of head and neck surgery and epidemiology at The University of Texas MD Anderson Cancer Center in Houston, it will be extremely difficult to prove that the HPV vaccine is effective in preventing oropharyngeal cancers. Unlike cervical cancer, for which the development of premalignant lesions is evident in abnormal PAP smears many years prior to the development of invasive cancer, there is no good way to detect similar precancerous changes in the oropharynx. Although some have suggested testing for HPV DNA by swabbing the throat, Dr. Sturgis recommended against this. “The problem is that even if you find HPV DNA in the throat, that doesn’t mean that cancer will develop, and thus there is no clear screening or prevention available,” he said, adding that HPV DNA can be detected in 5 to 10 percent of people at any given time. He echoed a common assumption that the viral oncogenic process in the oropharynx is basically the same as in the cervix, and it is therefore expected that the vaccine will prevent oropharyngeal cancers as effectively as it does cervical.